Port is closed on Azure Linux VM even though allowed by network security group (NSG)

Question

here's my scenario:

I have IP camera behind the company firewall that I want to stream publicly, and for that, I've created two Azure VMs (Ubuntu 19.04) - let's call them vm1 and vm2

In case it's important, my VM SKU is Standard B1s (1 vcpus, 1 GiB memory)

1. I SSH to my camera and from there, I do a remote port forwarding for RTSP like this:

   ssh -R 554:localhost:554 root@<vm1-ip>
   

   And, I guess I need to enable root SSH because it's a "well-known" port.

2. I log in to vm1, and I see it's listening on the port: sudo netstat -tlnp gives me this:

   Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
   tcp        0      0 127.0.0.1:554           0.0.0.0:*               LISTEN      108748/sshd: root@p
   tcp6       0      0 ::1:554                 :::*                    LISTEN      108748/sshd: root@p
   

3. But, when I use nmap from from vm2, the port is shown as closed:

   nmap <vm1-ip> -p 554
   
   PORT    STATE  SERVICE
   554/tcp closed rtsp
   

4. When I use vlc to connect to the stream, it doesn't work either: the URL I use in vlc is: rtsp://<vm1-ip>/...

5. I thought this might be an issue with the NSG (network security group) associated with vm1, so I tried allowing all inbound traffic: and, needless to say that it doesn't solve the issue

Any thoughts on this?

Thank you